The use of condition monitoring systems for wind turbines has increased significantly in the recent years as the main wind turbine components have increased in size and the components are also designed closer to the material limits.
It is possible with a condition monitoring system to continuously detect the activity of wind turbine components such as the wind turbine blades during normal use. Abnormalities in the function of the wind turbine component may be detected early, such as damage or wear to the component and removed in time before a full breakdown of the component.
A problem with the known condition monitoring systems is the fact that complexity of the wind turbine components makes it difficult to establish reliable reference curves to compare the measured values with.
An example of a known condition monitoring system for a wind turbine is disclosed in U.S. Pat. No. 7,072,784.
Consequently, it is necessary to provide the condition monitoring system with a large margin in order to compensate and ensure that any abnormality is detected. The condition monitoring system may however easily become imprecise with the compensation margin and thus cause a number of false alarms.
Further it is a problem that the many different sizes and types of wind turbine components require a significant database of reference curves in order to successfully apply condition monitoring systems to all modern wind turbines.
It is an object of the present invention to provide solutions for wind turbines without the abovementioned disadvantages in the prior art.